Within the past century, the Thai population has changed tremendously. The population rapidly increased from 8 millions in 1910 to 26 millions 50 years later (1960), and surged to 64 millions in 2010, an eight folds increase in a century. Particularly in the past 50 years, urbanization occurred, and jobs became more complex. These changes alter the economy, society, culture, and environment without leaving a trace of the old society.

Thailand proceeded through important demographic transition, which can be viewed from the reduction in mortality rate. Prior to the World War II, the mortality rate per 1,000 individuals per year is higher than 30. At present, the mortality rate is reduced to 7 per 1,000 individuals per year. The infant mortality rate, which was previously higher than 100 per 1,000 live births have reduced to not more than 15 per 1,000 live births.

Concerning the fertility rate, the Thai population has reduced fertility rate rapidly due to the promotion of family planning. Fifty years ago, a woman would have an average of 6 children, but this rate has reduced down to 1.5. At present, the Thai population has smaller family, and the trend continues of having less number of children in the future.

The demographic transition, particularly in the second half of the century, has huge impact on the age structure. With the reduction in younger generation, there are more elders than the young. Thus, Thailand is heading toward an aging population society.

Furthermore, as more people flood into the city due to economical, educational, and other reasons, the city copes by expanding rapidly, which leads to subsequent urbanization. As the urban population increases, people live in congested area. The quality of live became stressful and urgent, and is the opposite of life in the rural.

In addition, other social aspects that contribute to the demographic transition in this century include the flowing of jobseekers from the neighboring countries, Myanmar, Laos PDR, Cambodia, and Malaysia, into Thailand to work. Not only jobseekers, many foreign nationals choose to retire in Thailand. Many foreigners also marry Thai woman and live in Thailand. This is common in the Northeastern region of Thailand.